Description 
The While keyword starts a control loop that is executed as long as the Expression is satisfied (returns True).
The loop is not executed at all if the expression is false at the start.
You need Begin or End markers if multiple statements are required in the loop.
It is used when it is important that the statements are at only executed when necessary.


Related commands 
Begin 

Keyword that starts a statement block 
Boolean 

Allows just True and False values 
Do 

Defines the start of some controlled action 
End 

Keyword that terminates statement blocks 
For 

Starts a loop that executes a finite number of times 
Repeat 

Repeat statements until a ternmination condition is met 
Until 

Ends a Repeat control loop 


Author links 

Download this web site as a Windows program.




Example code : Display integer squares until we reach 100 
// Full Unit code. //  // You must store this code in a unit called Unit1 with a form // called Form1 that has an OnCreate event called FormCreate. unit Unit1; interface uses SysUtils, Forms, Dialogs; type TForm1 = class(TForm) procedure FormCreate(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} // Include form definitions procedure TForm1.FormCreate(Sender: TObject); var
num, sqrNum : Integer;
begin
num := 1;
sqrNum := num * num;
// Display squares of integers until we reach 100 in value
While sqrNum <= 100 do
begin // Show the square of num
ShowMessage(IntToStr(num)+' squared = '+IntToStr(sqrNum));
// Increment the number
Inc(num);
// Square the number
sqrNum := num * num;
end;
end; end.

Hide full unit code 
1 squared = 1
2 squared = 4
3 squared = 9
4 squared = 16
5 squared = 25
6 squared = 36
7 squared = 49
8 squared = 64
9 squared = 81
10 squared = 100


